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Lap Timing with RaceChrono Part 2

In my Lap Timing Part 1 post, I gave an overview of some of the benefits and features of using a lap timer like RaceChrono. In this post, I’ll explain how to install the RaceChrono software and how it works.

If you already have an Android phone then skip the next section. Those of you who have just bought an Android phone in order to be able to use RaceChrono read on.

Setting up your Android phone
In order to use Android, you need to link the phone to a Google account (email address) otherwise you cannot access Google’s Play App store. If you don’t intend using the phone for anything other than lap timing, I’d advise you to create a new Google account using the phone rather than using an existing Google account (for privacy reasons). The account isn’t really that important – if you lose or forget the account details, just wipe the phone, create another Google account and re-install RaceChrono again.

Usually you will be prompted to create or link your Google account when you first switch on your phone but don’t worry if you aren’t because you will be when you launch the Google Play app from your list of apps (on the phone).

Installing RaceChrono
google_playAndroid phones come with many pre-installed apps, but RaceChrono won’t be one of them! There is normally an icon on the home screen that gives you access to all the apps installed on the phone. Find and launch the (Google) Play app – it is this app that gives you access to Google’s App store. Older phones may have Google Market pre-installed instead of Google Play – don’t worry because Google Market will also allow you to find and install RaceChrono.

In Google Play, hit the search icon and type “racechrono” (all one word without the quotes). The RaceChrono app should be returned as the first search result. Tap on it. On the next screen that describes the app in more details, hit the Install button. You should see the app downloading and installing after that – it shouldn’t take more than a minute or two to install but that will depend on the speed of your network connection.

Launching RaceChrono
racechrono_iconReturn to your home screen, hit the icon that gives you access to all your (installed) apps and find the RaceChrono app in the list. Then tap on it to launch it.

device-2013-01-19-115353When you first launch RaceChrono, you will be asked to set up a RaceChrono account. Enter an email address and make up a password just for this account. Don’t use any existing password!! Within about 5 minutes, you will receive an email from RaceChrono with an activation link. Click on the link in the email to confirm your RaceChrono account details – you can receive the email and activate the link from any computer – you don’t have to do this on the phone itself!

Now hit the Sign In button and enter your RaceChrono account details. Don’t bother trying to enter your details until you have activated your account – it just won’t work!

Adding your tracks
device-2013-01-19-120132In order for RaceChrono to be able to calculate your lap times, you will need to add your circuit to list of circuits on the phone. Hit the Tracks button and select the Library tab.

There are nearly 400 circuits from around the world, so there’s every likelihood that your track is listed. Where different circuit layouts for the same track exist, normally this will be listed as separate circuits too, so you should always be able to locate the track/circuit that you need.

device-2013-01-19-120941Find your track in the list, and tap on it. The track will then be displayed on a Google Map. Above the map, you will see a download icon (downward arrow above a horizontal line). Tap on this icon, and the circuit will be downloaded on to your phone.

The significance of downloading the circuit into your phone is that RaceChrono then has access to the locations of the start/finish line and the split locations. And it can make use of this information when you’re at the track without requiring any network connectivity.

If you’re not sure whether you will be able to get a network connection, then make sure you install the circuit before you head to the circuit!

Using the Timer
Return to the RaceChrono start screen and hit the big red Start button. The timer will now be started for a new session and you will see the screen change.

device-2013-01-19-122735Three three vertical numbers signify your best lap time (this session), your previous lap’s time, and the current lap’s time. Above the numbers is an indication of the number of satellites that have been fixed and below in red is the circuit that you are riding at.

Although you can tap on the lower red band to select your circuit manually, there is no need as RaceChrono will automatically assign the track from your listed of downloaded tracks. However having said that, it is important to make sure that RaceChrono has figured out which track you’re at otherwise you won’t get any meaningful lap times.

Once you’ve started the timer, place the phone in pocket in your leathers or safely attach the phone to your bike so that it won’t fall off on track.

Reviewing your lap times
When you return to the pits after your session, hit the Back button on your phone. RaceChrono will ask you whether you want to stop recording – hit Yes and you will be returned to the RaceChrono start screen.

device-2013-01-19-124342In order to review your last session, hit the Sessions button.

The sessions screen will list all your sessions with the latest at the start of the list.

The following details are recorded for each of the sessions:

  • the circuit name
  • the date and time that the session started
  • the total number of laps that session
  • your best lap time that session

device-2013-01-19-124933If you tap on the session, you will be able to see a more detailed summary including a lap time for a theoretical “optimal” lap.

The optimal lap time for the session is calculated by taking the best split times for any of the laps in the session and combining them into one theoretical optimal lap.

Sometimes this time corresponds exactly to your best lap time, but sometimes your best lap time has a slower split than another lap which means that the optimal lap is theoretically faster.

Notice that Laps and Route panel on the window both have the legend, “Tap to analyze”. If you tap either panel, then more information will be displayed on the next screen.

The analysis screen for Route will show you your progress round the track for each lap. Its main usefulness is in allowing you to compare speeds, braking G etc at different sections of the track in different laps.

device-2013-01-19-142955The analysis screen for Laps is altogether more useful because it will give you the actual lap and split times for each of your laps that session.

The blue line (lap 4 here) denotes your quickest lap that session. Any green sectors (section 2 in lap 6) denote a sector where you rode faster than the same sector on your quickest lap – 0.21 seconds quicker in this example. The other sector times indicate how much slower you were in those sectors. The optimal lap is made up by taking the best sector times from all laps that session.

You can toggle between relative and absolute sector times, and split or sector times using the two triangles near the top right of the screen. Have a play with these to get a sense of what they tell you as the numbers on the screen change.

You might have noticed that lap 1 and lap 8 are “greyed out”. If you long press on a lap, a menu pops up with various options including one to make the lap as invalid. This is useful otherwise lap 1 would be shown as the quickest lap when it is in fact some kind of aberration. Lap 8 was caused by pulling into the pits and forgetting to switch off the lap timer for nearly 20 minutes!

Comparing laps
You can compare any two laps in a session by tapping on any lap from the list.

device-2013-01-19-145919In this example, I tapped lap 5 which is then displayed against your best lap (4 in this case). Lap 5 is the brighter line, while lap 4 is the slightly darker line – you can tell which is which by looking at the top of the screen as the two drop down triangles. Tapping either of these allows you to switch the two laps that you want to compare.

The graph here shows a higher entry speed into Druids with later braking – this in part would be one of the reasons for the faster lap time.

You can drag the lower graph left and right to replay the lap, and as you do so you can see your progress on the map above. You will also see the absolute numbers at the bottom of the screen change too – these can be useful to see the actual speed at a given point on the track.

device-2013-01-19-185643Speed is not the only variable that you can plot on the graph either. If you tap on the gear icon at the top right of the screen, you will bring up a menu that allows you to change the graph settings.

Tapping “GPS receiver channels” will produce a new menu for the lines you want plotted. Speed is selected by default, but you might want to see Longitudinal acceleration to gauge and compare your acceleration and braking forces.

The X-axis can be plotted by distance or time. If you select Distance, then ensure that the bottom setting “Scaled comparison X-axis” is set so that the two comparisons graphs coincide correctly.

It’s best to have a play with these settings after you’ve done your first track day because the numbers shown to you will make more sense than the example session which is preloaded into the app.

Lasting the day
Battery usage is a big concern on a track day where you might not have access to a phone charger. For that reason, I try and reduce the power usage on the phone as much as possible.

Before heading out on track, I enable Bluetooth (so the phone can communicate with my external Q818XT GPS) and also switch the phone into Airplane mode since I won’t need to take calls or receive emails out on track! I also switch off the phone’s inbuilt GPS because I’m using an external GPS.

When I get back from the session. I stop the timer, switch off Bluetooth and re-enable the phone’s network communications.

Once you start using RaceChrono, you’ll wonder how you ever managed without it. As a Track Day beginner, you’ll find it useful to see that you’re improving and where those improvements are coming from.

More expert riders will like the fact that they can quantify changes that they make to the bike including things like tyre or pressure choice, sprocket selection and/or suspension changes.

If you’re intending to use an external bluetooth GPS receiver with RaceChrono, then you’ll find this post on using the Q818XT external GPS useful – especially the information on device pairing.

QStarz Q818XT – 10Hz GPS receiver

The QStarz BT-Q818XT bluetooth GPS receiver is a 10Hz unit that is 100% compatible with RaceChrono. It also offers high poll rates, DGPS (differential GPS), AGPS (almanac GPS) and long battery life.

While most decent GPS units use the SiRFstarIII chipset, the 818 uses the relatively unknown and new MKT II chipset.

My experience with the 818XT has all been positive. It acquires satellites very quickly, and I’ve not had any bluetooth issues with the connection to my Android phone. However, I was confused by a few of the features and settings when I first started using it, so hopefully this blog post will help answers some of the questions I originally had … as you might be having them too.

There is a 3 position on-off switch on one side of the unit; those positions being Off, 1Hz and 10Hz. The differential (DGPS) capability is not enabled when operating at 10Hz, but is available when the switch is in the 1Hz (middle) position. However, 1Hz is not really fast enough for reliable lap timing, so what can be done?

Well, you can download the Windows drivers and the GPS View application (for Windows only) which will allow you to reconfigure the 1Hz switch setting to a frequency between 1 and 5Hz. You can find the downloads for the 818XT at QStarz Downloads page – select “GPS Receiver” as your product type and choose your exact model from the secondary (right hand) menu. There are also links to a quick quide and full user manual.

After installing the driver and application, connect your Q818XT to your computer and switch it on to the 1Hz setting. Open Settings->Control Panels and select the System control panel. Switch to the Hardware tab and look to see which LPT/COM port the 818 is listed as being connected to. Launch the GPS View application and set the appropriate COM port at the top of the window. You should then see the GPS messages scrolling in the top left panel of the window – if you don’t then you have probably selected the wrong COM port.

If you switch to the Setup tab, you can change the frequency for the middle (1Hz) switch position. Look for the section that says “Fix Update Rate” and hit the Query button. It should report 1Hz in the Data Bandwidth box to the right. Since we want 5Hz instead of 1Hz, all you need to do is change the rate in the pulldown menu from 1 to 5 and hit the Set button. That’s it, the 1Hz switch position will now operate the unit at 5Hz with full DGPS capabilities. It will remain at 5Hz until you pull the battery out of the unit or possibly until the battery runs completely flat.

Just remember to make sure you select the middle (1Hz) setting instead of the 10Hz switch position before you head out on track! In my opinion, a 5Hz refresh rate with DGPS is more valuable than a 10Hz rate without DGPS as the position reports will be both frequent enough and have a greater accuracy.

The AGPS feature is less important for accuracy as it primarily affects how long the unit takes to get its first fix. It does this by updating its internal almanac which enables it to locate the appropriate satellites more quickly. You can use the Update button in the lower panel to download a new almanac automatically from the internet. The new almanac will last for 6 days, and you can update it as often as you like.

Bluetooth Pairing
Pairing this unit with your phone should be simple. Enable Bluetooth on your phone, switch on the Q818XT and it should show up in the list of available devices. The pairing code will be “0000” (four zeroes).

Make sure you change the “GPS receiver type” setting in RaceChrono to be “Bluetooth device” and select the QStarz 818XT as the external GPS device.

Unit Location
In order to give the unit decent line of sight with the satellites in the sky, I mount the unit on the tail of the bike. The 818XT has a rubberised bottom which is placed on the tail unit, and the whole thing is then taped to the tail.

I used a lot of tape; firstly to ensure that the receiver doesn’t fall off (?!) and secondly to try and form a waterproof barrier around the switch and the USB connector. Since the device lasts for 24-40 hours on a single charge you can switch it on before taping it to the bike, and then leave it on for the full track day.

Pre Track Day Preparation
I usually charge the unit for 2-3 hours before a track day. Using QStarz’s GPS View software, I also upload the latest almanac(which lasts for 6 days) and double-check that the 1Hz switch position is still re-mapped to 5Hz.

That’s really all you need to know about this receiver.

If you want background on using the QStarz 818XT then have a read of this post on how to set up and use a lap timer.

Update Summer 2014

You might be interested in reading a comparison between the QStarz 818XT and the Garmin Glo.

Lap Timing Part 1

One of the most useful tools to measure your progress on track is a lap timer.

A lap timer enables you to “see” how changes in your riding style, race line, tyre choice, gearing or suspension setup affect your lap times.

Normally these devices cost from a few to many hundred of pounds (or dollars) depending on which make you buy and the features that it offers.

How would you feel if I told you that you could potentially have all this lap timing capability for free?

Pretty excited, I’d imagine…

With the advent of smart phones, this is a reality because a small group of Finnish software developers created a lap timer called RaceChrono for mobile phones. It runs on Symbian (Nokia), Windows (Mobile) and Android devices. Sadly, there isn’t a version of RaceChrono that runs on iPhones so those users might want to consider getting a “cheap” Android phone to use instead.

If you have one of these phones that can run RaceChrono app then you can get a fully featured lap timer… for free. Yes.. you read that right! All you need do is to ensure is that your phone incorporates a GPS receiver or has bluetooth capability built-in to allow it to connect to an external bluetooth GPS receiver. Without some form of GPS, RaceChrono cannot work.

How it works
RaceChrono has details of over 400 tracks around the world including different track layouts for the same circuit. The track at Brands Hatch for example has two layouts; the Indy circuit or the full GP circuit.

Each track has a start/finish line recorded as well as the location of either one or two additional split time markers.

As you ride around the track, RaceChrono will use the GPS receiver to determine where you are on track (up to 10 times a second). In this way, RaceChrono is able to determine when you pass the start/finish line or any of the other split timing markers. As you do this repeatedly during your track session, RaceChrono will mark off each lap and calculate your lap and split times automatically.

In order to use RaceChrono for your track day, just choose your circuit (and track layout) from the list. If the track doesn’t exist in the list then you always have the option of adding your own track and defining the start/finish line and any additional split timing markers that you want or need.

Just before you start your session, switch the app on to record, slip the phone into your pocket or attach it securely to your bike, and you’re good to go. There is no need for any external track side timing equipment for the app to work – just clear line of sight to the satellites in the sky.

In fact RaceChrono works so well, that anecdotal evidence suggests that it is accurate to within a few hundreths of a second compared to the times reported by official track side timing equipment.

But, that accuracy comes at a (small) cost…

The internal GPS units built into most phones, while often very accurate, cannot sustain a high poll rate. This means that they often cannot report a position fix more frequently than once a second. When you’re travelling at 100mph (160kmh) that equates to a distance between two fixes of around 48 yards (44 metres). A GPS unit that can operate at 10Hz (polled 10 times a second) will get a fix every 4 metres when travelling at 100mph. The faster the GPS can be polled, the more accurate your lap times will be.

A further issue affecting accuracy is that the phone internal GPS receivers normally don’t have a differential capability (DGPS) built into them. If they did, it would allow them to compensate for the selective inaccuracy that the US military build into the GPS network.

You can overcome both this issues by using RaceChrono in conjunction with an external Bluetooth GPS receiver. Two popular ones are the Garmin GLO and the QStarz 818 series – these typically cost between £50-90 (US$90-150) depending on the unit.

In the case of the QStarz 818XT (which I have), the DGPS capability is disabled at 10Hz, but can be enabled by running the unit at 5Hz instead. 5Hz means a position fix every 1/5 of a second and is perfectly good enough for accurate lap times, especially since the position accuracy is enhanced by the DGPS capability being enabled.

Although you might be wondering whether to bother with the hassle and cost of an external receiver, it is worth noting that in addition to providing inherently better accuracy, you can also mount these units so that they will have a better view of the sky compared to a phone in your pocket. Popular mounting points include on/under the tail or under the fairing bubble. All you need is some gaffer/duct tape to stick the unit in place.

Relying on the internal GPS of a phone stuffed into your pocket when your body is shielding much of the sky could lead to poorer quality position fixes at certain points on the track and as a result less accurate lap and split times.

Now that we’ve covered the preliminaries, I’ll explain how the app works in more detail in Part 2 of this article.